JPH01168840A - Sliding frictional member made of cast iron - Google Patents

Abstract

PURPOSE:To obtain a frictional member showing excellent damping effect from the beginning of its use by manufacturing the sliding frictional member such as a disk rotor, etc., for a pad in a disk brake of an automobile with the cast iron of ferrite structure contg. hard metallic carbide and spheroidal graphite. CONSTITUTION:A disk rotor 2 for a pad 4 of the sliding frictional member made of semi-metal in a disk brake 1 of an automobile is manufactured with low alloy cast iron of the compsn. contg. small amounts of W, V, Cr, etc., as hard carbide forming elements. The disk rotor 2 made of the cast iron is cast, is left cool, is thereafter annealed for 6hr at 700 deg.C and is cooled by a furnace. In the sliding surface 5, ferrite is regulated to its matrix and the material is reinforced by spheroidal graphite cast iron as a solid lubricant to form the structure in which the hard carbide of W, V and Cr as a frictional material is deposited in the fine shape of <=40mum by 1-10areal%. The disk rotor 2 made of cast iron whose coefficient of friction for the sliding frictional member 4 does not change on standing from the beginning of its use can be obtd.

Description

[Detailed Description of the Invention] <Industrial Application Field> The disclosed technology applies to
It belongs to the field of technology for the structure of a cast iron sliding friction member that increases the friction coefficient of the friction surface of a pad provided opposite to a disc rotor.

Therefore, the present invention relates to a sliding friction member that is used for braking by the contact friction between the two, such as a disc rotor for a disc brake pad of an automobile, etc. This invention relates to a cast iron sliding friction member such as a disc rotor in which one sliding friction member such as a semi-metallic pad having a small coefficient is used as a sliding partner, and in particular, the base portion is structured with ferrite, The shape of the graphite is made spheroidal, and further
This invention relates to a cast iron sliding friction member characterized in that carbides having the following sizes are precipitated in an area ratio of 1 to 10%.

<Prior Art> As is well known, various mechanical devices are assembled with a plurality of complex members, and among these, a plurality of relative sliding friction members come into contact with each other, resulting in, for example, There are some devices which are used as constituent members of automobile braking devices and clutch devices, which are disclosed in the applicant's earlier inventions, Utility Application No. 180485/1985 and Japanese Patent Application No. 22977/1983.

Therefore, at present, solid lubricants such as metal fibers, metal powder, and graphite are the main ingredients, and are hardened with binder resin, which have excellent wear resistance and friction stability in high-temperature areas. So-called semi-metallic pads are used as pads for disc brakes.

Examples of such technology include sliding friction members such as brakes and clutches that utilize the effect of contact friction between the two, such as a disc rotor installed against a disc brake pad. A combination of slides in which the surface portion is made of pearlite or ferrite, or where the other sliding friction material, such as a pad that works to convert the friction between a pair of opposing sliding friction members into braking force, is flake graphite cast iron. Some have a moving member structure, and some have graphite protruding from the rotor surface.

<Problems to be Solved by the Invention> However, the disadvantage of semi-metallic pads over disc rotors is that the coefficient of friction increases in proportion to the number of times the brake is used, and the effectiveness of the brakes also improves. Sometimes the coefficient of friction is low and the effectiveness is poor.

The lid and nuclide semi-metallic pad are in new condition.
This is because during friction, it is difficult to make contact with the disc rotor, and only a portion of the friction surface actually operates.

Another disadvantage of semi-metallic pads is that their specific gravity is higher than that of organic friction materials, with the same volume weighing 20 to 5.
The disadvantage is that it is 0% heavier, difficult to assemble, and leads to worse fuel efficiency.

Furthermore, since the temperature of the back metal of the pad increases, it becomes necessary to interpose a heat insulating material between the back metal and the pad in order to prevent the paper lock phenomenon, etc., resulting in a problem that the structure becomes complicated.

The object of the present invention is to solve the problems of semi-metallic brake pads based on the above-mentioned prior art, and to solve the problem of semi-metallic brake pads, etc. By making use of the advantages of using a sliding friction member while compensating for its disadvantages, and by making the sliding friction at the initial stage of use similar to the sliding friction during use over time, the application of sliding technology in the machine manufacturing industry is achieved. It is an object of the present invention to provide an excellent cast iron sliding friction member that provides improved performance.

In order to solve the above-mentioned problems, the structure of the present invention, which is based on the above-mentioned object and the gist of the above-mentioned claims, is to solve the above-mentioned problems by using a plurality of opening friction frictions, such as disc brakes of automobiles. In a sliding member of a braking device that uses relative friction between members, one sliding friction material made of cast iron or the like has a small initial coefficient of friction, and graphite is spheroidized in the base structure. This improves the friction with the other friction member from the initial state, and takes technical measures to improve wear resistance by adding elements that have a higher tendency to form carbides than iron to precipitate carbides. It is.

<Background of the Invention> Therefore, carbides with a size of 40μ or less have an area ratio of 1 to
The reason for precipitating 10% is that if it is less than 1%, the wear resistance of one friction sliding member deteriorates, and if it is more than 10%, the effect of increasing the friction coefficient of the other sliding member is small.

The reason why the carbide is set to be 40 μm or less is because if it is 40 μm or more, the effect of improving the coefficient of friction is small, and the type of additive may be set to a predetermined value. It is preferable that the hardness is equal to or higher than that of the abrasive agent contained, and for example,
Examples include tungsten, titanium, chromium, and molybdenum.

Alternatively, the annealing may be performed at a temperature lower than the A1 transformation point in order to decompose only the matrix leaving the carbide and turn the matrix into ferrite.

<Example> Next, an example of the present invention will be described below based on FIGS. 1 to 6.

In the embodiment shown in FIG. 1, reference numeral 1 is a disc brake of an automobile, and one sliding friction member, which constitutes the gist of the present invention, is a cast iron disc rotor 2, and the other sliding friction member is supported by calipers 3 on both sides. A pair of pads 4.4 as members are provided facing each other, and the structure other than the disc rotor 2 is formed to be substantially similar to that of a conventional disc brake.

The disc rotor 2 has a friction sliding surface 5.5.
During this process, the pad 4 comes into contact with the pad 4, and the mutual contact friction is used for braking the automobile.

Therefore, the disc rotor 2 as one sliding friction member
is made of cast iron and is formed through processes such as casting and grinding, and its material composition is as shown in the table below.

* Moreover, the method of modeling is as follows.

First, the materials with the above ingredients are cast, and after cooling, 700
After annealing at ℃ for 6 hours, it is cooled in a furnace.

Then, it is formed into a predetermined shape by machining.

As a result, the area ratio shown in Figure 2 was 6% and the size was 15 μm.
Disk play kg with less carbide.

-You can get evening.

Further, the pad 4 as the other sliding friction member is made of semi-metallic material as in the conventional embodiment.

In the above configuration, when the disc brake 1 is subjected to actual use or testing, the pads 4.4 come into contact with the ferrite structure 6 on the surface layer of the disc rotor 2 at the initial stage of use, and the pad 4.4 contacts the ferrite structure 6 on the surface layer of the disc rotor 2. Although it is a disc rotor 2, since the surface on the disc rotor 2 side has a ferrite structure with spherical graphite interspersed therein, it is frictionally engaged with the pad 4 from the initial state with a high friction coefficient.

Therefore, sufficient sliding friction can be obtained from the initial stage of use, and stable precision can be achieved.

Of course, the high coefficient of friction due to the spheroidal graphite is maintained even after use over time.

Further, since carbide is mixed in the range of 1 to 10%, not only the disc rotor 2 itself but also the pad 4 do not wear out and have good durability.

The friction and wear test results of the disc rotor 2 were then conducted as shown in Fig. 3.4.

The test conditions were to use semi-metallic material as the pad material,
Using this invented product and new conventional materials as disc rotor materials, the initial braking speed was 50 using a full-size friction and wear tester.
KIR/h1 braking deceleration 0.3G, braking interval 120 seconds,
And, the number of braking was 500 times.

The test results showed that the initial friction coefficient μ of the first time was improved by 0.15 in the case of the invented product compared to the conventional material.

The coefficient of friction μ during the stable period after the 200th test also improved by 0.05 on average.

Furthermore, there was no difference in the amount of rotor wear between this invention and the conventional material.

In addition, when we conducted a test in which the area ratio of the carbide was varied while keeping the size constant at 20 μm or less, as shown in Figure 5, the friction coefficient and rotor wear amount were large for the conventional material regardless of the area ratio. , dotted line - friction coefficient, solid line - rotor wear amount, wear resistance deteriorates when the area ratio is 1% or less, and the area ratio is 10%.
In the case of the product of this invention, which has a small effect of improving the friction coefficient, both the friction coefficient and the amount of rotor wear are high when the area ratio is small, but as the area ratio becomes large, both the friction coefficient and the amount of rotor wear become small.

Furthermore, when the area ratio is kept constant at 6% and the size of the carbide is changed, the frictional properties are as shown in Figure 6. As the particle size becomes 40 μm or more, the effect of improving the friction coefficient becomes smaller. Ta.

Further, other examples are as follows.

The disc rotor 2, which serves as one sliding friction member, is shaped through processes such as casting and grinding, and the numbers are volume ratios.

Moreover, the method of modeling is as follows.

First, after casting the materials with the above ingredients and letting them cool, 720
After annealing at ℃ for 5 hours, it is cooled in a furnace.

Then, predetermined machining is performed to form the required shape.

Furthermore, the results of this example were almost the same as those of the above-mentioned example.

It goes without saying that the embodiments of the present invention are not limited to the above-mentioned embodiments. For example, the sliding friction member can be used not only for automobile disc brakes but also for functionalizing sliding friction in braking devices for machine tool blocks, etc. It can be applied to various other devices for taking out.

<Effects of the Invention> As described above, according to the present invention, in one of the pair of cast friction sliding members, the matrix is made into ferrite, so that the coefficient of friction is increased from the initial state, and the effectiveness of friction is improved. The effect of becoming Qin.

In addition, the area ratio of elements with higher carbide forming ability than iron is 1 to 1.
Since it is set to 0%, the effect is that if it is 1% or more, the wear resistance of one sliding friction member is improved, and if it is 10% or less, the wear resistance of the other sliding friction member is also improved.

Furthermore, the durability of the sliding friction member has been improved, eliminating the need for frequent replacement and reducing the number of maintenance inspections.
Furthermore, the overall weight of the device can be reduced, resulting in lower costs.

Specifically, the matrix hardness of this invention is approximately 180
HV, approximately 300HV of pearlite matrix
Compared to Qin, there is a significant softening effect.

Generally, when the matrix becomes soft, the wear resistance decreases, but in this invention, on the other hand,
By spheroidizing the graphite, it increases strength, prevents the progress of wear, and precipitates various carbides, and also improves safety by improving the effectiveness of brakes when new.

In addition, since uneven wear of the pads and the like is less than before, the number of replacements of the pads is reduced, leading to cost reduction.

[Brief explanation of the drawing]

3.4. 5.
Figure 6 is a graph showing the test results. 4... Semi-metallic sliding friction member (pad), 2... Cast type 1 dynamic friction member (disc rotor),
6... Ferrite structure part 6-h5441 Buddha a Wuga 2 figure ”

Claims (1)

[Claims] In the other sliding friction member made of cast metal, in which the relative contact friction with one sliding friction member is functionalized through the material matrix, the surface layer of the material matrix is made into a ferrite structure, the graphite shape is made into a spheroid, and the graphite shape is further 40 μm thick. A cast iron sliding friction member characterized in that carbides having the following sizes are precipitated in an area ratio of 1 to 10%.